Field of the Invention
The invention relates to a protein assay method.
Description of the Related Art
Protein assay methods include the Kjeldahl method, the Biuret method, the Lowry protein assay, the ultraviolet absorption method and the Coomassie brilliant blue method. However, the methods cannot differentiate protein nitrogen from non-protein nitrogen accurately.
Hydrolyzing proteins into amino acids and then analyzing the amino acids can learn the varieties and concentrations of the amino acids which constitute the proteins and evaluate the protein quality.
Conventional protein hydrolysis methods include acid hydrolysis method, alkaline hydrolysis method and enzyme hydrolysis method. The acid hydrolysis method damages tryptophan, decomposes a small amount of hydroxy-amino-acid (serine and threonine) and deaminates asparagine and glutamine. The alkaline hydrolysis method racemizes amino acids and deaminates arginine to produce ornithine and urea. The enzyme hydrolysis method requires a plurality of enzymes to hydrolyze proteins, and therefore, it is costly and inefficient.